Electrical contact devices for high voltage electrical systems

ABSTRACT

An electrical device in the form of an electrical connector for making a connection between complementary electrical contacts, shown in the form of a pin and a socket, under high voltage fault conditions, the device including a sleeve of arc-quenching material for guiding the pin into contact with the socket, the sleeve being axially spaced from the socket to provide a gap between the sleeve and the socket, and a metallic tubular member surrounding the gap and contacting the socket, the wall of the tubular member being radially spaced from the pin such that the gap has a longitudinal length no less than the order of magnitude of one-half the distance between the pin and socket at which an arc will be struck between the pin and the socket as the pin approaches the socket under high voltage fault conditions and a lateral width no less than the order of magnitude of one-half the same arc-strike distance.

[15] 3,6545% Apr. 4, 1972 United Mates Patent Brown [54] ELECTRICALCONTACT DEVHCES FOR HIGH VOLTAGE ELECTRICAL Primary Examiner+Richard E.Moore SYSTEMS AttorneySamuelson & Jacob [72] Inventor: Robert R. Brown,Bernardsville, NJ.

Assignee: Ameraca Esna Corporation, New Y rk, An electrical device inthe form of an electrical connector for NY. making a connection betweencomplementary electrical conpin and a socket, under high volteviceincluding a sleeve of arctacts, shown in the form of a age faultconditions, the d Dec. 30, 1969 Filed:

quenching material for guiding the pin into contact with the socke [21]Appl. N0.:

aced from the socket to proa gap between the sleeve and the sockettubular member surroundin socket from the pin such that the t, thesleeve being axially sp vide , the wall of the tubul than the order ofmagnitu [52] U.S. CI. [51] Int Cl [58] Field ofSearch.............

the pin and socket at which an arc will be struck between the pin andthe socket as the pin approaches the socket under high voltage faultconditions and a lateral width no less than the order of magnitude ofone-half the same arc-strike distance.

UNITED STATES PATENTS 3,323,097 5/1967 Tordoff ...l74/73 X 3,513,4375/1970 McMorris .........200/144 X 12 Claims, 3 Drawing FiguresPATENTEDAFR 4 I872 3,654,590

SHEET 1 BF 2 IN VENTOR.

ROBERT R. BROWN PATENTEDAPR 4 I972 SHEET 2 BF 2 INVENTOR. ROBERT R.BROWN HIS ATTORNEYS ELECTRICAL CONTACT DEVICES FOR HIGH VOLTAGEELECTRICAL SYSTEMS The present invention relates generally to electricaldevices such as switches and connectors for use in high voltageelectrical systems and pertains, more specifically, to electricalswitches and connector elements which employ arcquenching materials forinterrupting an electric arc ordinarily struck during connection anddisconnection under high voltage load conditions, and embodying meansfor accommodating gases generated by the arc so that such connection anddisconnection may be accomplished without failure of the switch orconnector structure and means for accommodating an arc which will bestruck when a connection is made under high voltage short circuit, orfault, conditions.

It is now commonplace to find electrical switches and disconnectableelectrical connectors employed in a variety of locations in high voltageelectrical distribution systems. While it is always best to make orbreak such disconnectable connections or throw the contacts in suchswitches under no-load conditions, it is not always easy or expeditiousto determine whether or not high voltage is present in a switch or in aconnection and then assure that no voltage is present before throwingthe switch or disconnecting the connection or reconnecting theconnection. Thus, connections and disconnections are constantly beingmade under high voltage load conditions. Additionally there is presentthe risk of inadvertently making a connection to a faulted circuit, thatis, making a connection under short circuit conditions, and such devicesshould be capable of withstanding such an occurrence.

The use of arc-quenching materials in switches or other types ofelectrical connectors is now well known in the art. For example, inelectrical connectors which employ complementary pin ad socket contacts,arc-quenching material has been utilized in the form ofa tip placed uponthe pin and a complementary sleeve placed ahead of the socket such thatthe tip and the sleeve will accurately guide the pin into contact withthe socket while providing arc-quenching material between the pin andthe socket as the pin approaches the socket. As the pin and the socketare closed in under high voltage fault conditions in such connectors, acircuit will be established well before the pin engages the socket bythe striking of an arc, and since the arc must exist between thesurfaces of the arcquenching material of the tip and the sleeve, largevolumes of evaporation products will form and such products, whenconfined in the relatively small volume of the interior of theconnector, can create sufficient pressure to preclude complete closureof the connector with the result that the connector can burn up, perhapsbackfire or even explode with varying degrees of violence, dependingupon the materials selected. In an effort to prevent such undesirableeffects, some electrical connectors have been constructed with ventswhile others have been constructed with expansion chambers.

Electrical connectors employing vents are illustrated in US. Pat. No.3,413,592. The use of such vents has been found to be undesirable sincea vent will allow the carbonaceous materials as well as otherelectrically conductive and undesirable materials in the gases to beexpelled into the atmosphere where restrike of the electrical circuit ispossible, or in some instances, the vents expel gases into the interiorof an electrical oil-filled device, such as a transformer, thuscontaminating the oil and introducing the possibility of an electricalfailure within the transformer.

Electrical connectors employing expansion chambers are illustrated inUS. application Ser. No. 730,807, filed May 21, 1968, now U.S. Pat. No.3,539,972. The use ofsuch expansion chambers within the electricalconnectors themselves eliminates the problems introduced by the use ofvents; however, such expansion chambers are rather limited in volume dueto the limitations placed upon the maximum practical size of theconnector elements themselves and, under aggravated conditions, thelimited volume of these expansion chambers has been found to beinadequate in accommodating all of the gases produced by the arc.

It has now been found that the amount of gas generated by the arc can begreatly reduced by the introduction ofa gap of minimum prescribeddimensions between the sleeve of arcquenching material and the socketand by surrounding the gap with a wall of conductive material,preferably in the form of a metallic member.

It is therefore an important object of the invention to improve theperformance and reliability of electrical contact devices, such aselectrical switches and electrical connectors,

which use solid arc-quenching materials to interrupt the electrical arewhich appears during the breaking of an electrical connection under highvoltage load conditions in order to enable successful connection underfault conditions without a disastrous failure of the device.

Another object of the invention is to reduce to an absolute minimum thevolume of gases created during the closing of contacts in a device asdescribed above under high voltage, short circuit conditions therebyenabling the device, when enclosed, to be enclosed within a container ofsmallest possible volume, the small size being particularly desirablewhen used in conjunction with underground distribution systems.

A further object of the invention is to provide an electrical contactdevice of the type described above having a relatively simpleconstruction capable of economical fabrication.

The above objects, as well as still further objects and advantages, areattained by the invention which may be described briefly as providing,in an electrical device, such as an electrical connector element, inwhich electrical contact is to be made between at least a first contactand a complementary second contact under high voltage fault conditionsby movement of the first contact into engagement with the secondcontact, means for guiding the first contact for movement along a pathof travel leading to the second contact and providing a guide ofarc-quenching material for receiving the first contact prior toengagement of the first contact with the second contact, the guide beingspaced longitudinally from the second contact in the direction ofmovement of the first contact, and means for surrounding the spacebetween the guide and the second contact and providing a wall ofelectrically conductive material juxtaposed with the sleeve and thesecond contact and spaced laterally from the path of travel of the firstcontact, the wall being electrically connected to the second contact,the longitudinal spacing between the guide and the second contact andthe lateral spacing between the wall and the path of travel providing agap having a longitudinal length no less than the order of magnitude ofone-half the distance between the first and second contact at which anarc will be struck between the contacts as the first contact approachesthe second contact under high voltage fault conditions and a lateralwidth no less than the order of magnitude of one-half the samearc-strike distance.

The invention will be more fully understood, while still further objectsand advantages thereof will be made apparent, in the following detaileddescription of an embodiment of the invention illustrated in theaccompanying drawing, in which:

FIG. 1 illustrates complementary electrical connectors with a connectorelement constructed in accordance with the invention shown in alongitudinal cross-sectional view;

FIG. 2 is an enlarged fragmentary cross-sectional view of portions ofthe connectors of FIG. 1 as the connectors are being connected; and

FIG. 3 is a further enlarged fragmentary cross-sectional view of aportion of FIG. 2.

Referring now the the drawing, and particularly to FIG. 1, an electricalconnection is to be made between a high voltage cable 10 and atransformer 12 in a high voltage electrical distribution system. Thehigh voltage cable 10 has a central conductor 14, which is covered withan insulating jacket 16 which, in turn, is sheathed within a conductiveshield 18. The cable 10 is terminated within an electrical connectorelement 20 shown in the form of an elbow having a body 21 which includesan inner member 22 of insulating elastomeric material and an outermember 24 of conductive elastomeric material.

A central electrical contact is shown in the form of a pin 26 ofconductive metal projecting axially through a receptacle 28 in the body21 of the connector element 20. A tip 30 of nonconductive plasticarc-quenching material is affixed to the end of the pin 26 for purposeswhich will be described hereinafter.

Affixed to the transformer 12, and projecting outwardly of the casing 32thereof, is an electrical connector element constructed in accordancewith the invention and shown in the form of a transformer bushing 34.Bushing 34 is provided with a housing 36, preferably fabricated of anelastomeric material and having an axially projecting outer body portion38 constructed of a dielectric material, preferably an insulatingelastomer. Within the housing 36 is an electrical contact 39 shown inthe form of a metallic socket 40 having a plurality of segments 42 whichare biased radially inwardly by an annular spring member 44 whichencircles segments 42 adjacent the mouth 46 of the socket 40. A sleeve48 constructed of a plastic arc-quenching material is located ahead ofthe socket 40 within the housing 36 and has an axially directedcylindrical bore 50 having an inside diameter complementary to theoutside diameter of the plastic tip 30 and the pin 26 of the corresponding connector element for receiving and guiding the plastic tipand the pin into proper engagement with the socket as the connectorelements 20 and 34 are connected.

Both the electrical contact 39 and the plastic sleeve 48 are actuallyaffixed to a first tubular member 52 adjacent one end 53 thereof, thesleeve 48 being affixed to a portion 54 of the tubular member 52 bycooperating screw threads while the contact 39 is affixed to a portion55 of the tubular member 52 by cooperating bead-like deformations. Thefirst tubular member 52 extends axially to the other end 56 thereofwhere the tubular member 52 is terminated by a base 58. The base 58 hasa threaded aperture 59 so that the bushing 34 may be removably securedto a threaded stud 60 carried by a well member 62 which is permanentlysecured to the transformer casing 32. The threaded stud 60 ismechanically affixed and electrically connected to a lead 64 of thetransformer 12. The first tubular member 52 and the base 58 areelectrically conductive and are preferably constructed of metal. Thefirst tubular member 52 and the base 58 thus establish a cavity 66within the bushing 34.

A second tubular member 68, which is actually an integral portion of theelectrical contact 39, extends axially into the cavity 66 and has anannular wall 70 spaced radially from the first tubular member 52 andclosed off by an end wall 72 secured thereto, thus establishing dividingmeans for dividing the cavity 66 into a first chamber 74 and a secondchamber 76. The first chamber 74 is in open communication with passages78, established between the segments 42 of the socket 40, and with theinterior of the socket, while the second chamber 76 is sealed off fromthe housing 36 by the first tubular member 52 and the base 58. Aplurality of apertures 80 are spaced circumferentially around and extendradially through the annular wall 70 of the second tubular member, andvalve means 81 shown in the form of an annular band 82 of elastomericmaterial normally closes the apertures 80 by virtue of the resilience ofthe elastomeric material of the band. The annular band 82 is seatedwithin an annular recess 83 in the annular wall 70 so as to bepositively retained against axial movement along the second tubularmember 68.

As best seen in FIG. 2, as the complementary connector elements 20 and34 are brought together, the plastic tip 30 will cooperate with theplastic sleeve 48 to serve as a pilot or guide for aligning therespective electrical contacts prior to the making of any electricalcontact between these contacts and prior to actual engagement of the pinwith the socket. As the connector element 20 is pushed toward fullengagement with the bushing 34, the metallic pin 26 will approach thesocket and an electric arc may be struck between portions A and B,immediately causing a rapid generation of gases C which could eitherpreclude a full engagement of the connector elements by establishing aback pressure or could cause an explosive failure of the bushing 34.However, since the socket 40 provides an internal path between the arcand the interior of the socket in the form of passages 78, which path isin open communication with the first chamber 74, the gas C can flow intothe first chamber and, as the volume available in the first chamber forthe gas decreases by virtue of the penetration of the contact pin 26 andtip 30 and the pressure of the gas builds up in the first chamber 74,the annular band 82 will dilate resiliently to allow such pressure to berelieved and the first chamber will be vented through the valve means 81into the second chamber 76. Thus, the cavity 66 provides the volumenecessary to relieve the internal pressure which could otherwise buildup to an intolerable level so as to permit completion of the connectionbetween the metal pin 26 and the socket 40 before the uncontrolledgeneration of very large volumes of gas can take place with concomitantdeleterious effects. Immediately upon the completion of such aconnection the electric arc is extinguished and no further gases aregenerated. Completion of the connection enables the axially projectingbody portion 38 of the housing 36 to be seated within the receptacle 28of the complementary connector element 20 to establish a watertightconnection.

it is noted that bushing 34 provides an extra measure of pro-' tectionagainst violent explosive failure and flying debris when the housing 36is constructed of an elastomeric material. Should the volume of gasesgenerated by an electric arc become so great as to cause the bushing toburst, such a failure would merely rupture and tear the elastomericmaterial and would not tend to throw harmful fragments which couldinjure persons in the vicinity of the connector.

Upon disconnecting the complementary connector 20 from the bushing 34under high voltage load conditions, an electric arc may be struck as themetallic pin 26 is withdrawn from the socket 40 and again approaches theposition shown in FIG. 2. It is desirable to extinguish this arc asquickly as possible and to restrain any gases which may be generated bythe arc so that the arc will cause no damage and ionized gases do notescape and restrike an arc to ground which could injure personnel in thevicinity of the connection. As the contact pin 26 and the plastic tip 30are withdrawn from the socket 40 and the first chamber 74, a partialvacuum is established in the first chamber 74 by virtue of thewithdrawal of the elements formerly occupying the socket 40 and thechamber 74, and the closing of the valve means 81 to maintain theavailable volume of the chamber 74 relatively small. Since the ambientpressure will now be greater than the pressure within the first chamber,the gases generated by the electric arc will be drawn into the firstchamber 74 and held there by the higher ambient pressure outside thebushing 34 until the contact pin 26 is withdrawn far enough for the arcto be extinguished. Hence, the combination of the first and secondchamber 74 and 76, respectively, with valve means 81 between thechambers provides adequate volume for accommodating gases generated uponconnection of the complementary connector elements to enable completeconnection without back pressure under many high voltage faultconditions and provides a more limited volume upon disconnection of theconnector elements under high voltage load conditions to restrain gasesgenerated upon disconnection of the elements under such conditions.

Since the second chamber is of limited volume by virtue of cavity 66being wholly within the bushing 34, it will be seen that dissipation ofenough of the gases entrapped within the second chamber should takeplace prior to making another connection at load so that any furthergases generated during such a subsequent connection can be accommodated.Hence, the gases which have been trapped within the second chamber 76may be allowed to dissipate slowly and preferably back into the firstchamber '74 and thence out of the connection by passing through passages78 between the segments 42 of the socket 40 and the cylindrical bore 50of the plastic sleeve 48. To this end, a plug 88 of porous material,such as a porous member of sintered metal, is placed in the end wall 72to allow slow leakage of gas from the second chamber 76 to the firstchamber 74 when the valve provided by the annular elastomeric band 82 isclosed over apertures 80.

it has been discovered that the volume of gases generated by the arcwhich is struck as the complementary contacts in the form of pin 26 andsocket 40 are closed in under a high voltage, short circuit or faultcondition may be reduced considerably by the provision of a gap 90 ofprescribed axial length L between the sleeve 48 and the socket 40. Bythus reducing the volume of the gases C, the above describedconstruction, which includes an expansion chamber in the form of secondchamber 76, has been found to operate successfully under extremeconditions which, in a construction which did not include such a gap,previously caused failure of the bushing 34.

Turning now to FIG. 3, the construction of the connector element in theform of bushing 34 in the vicinity of the gap 90 is illustrated in agreatly enlarged fragmentary view which shows the pin 26 located at adistance D from the socket 40 as the pin is being advanced intoengagement with the socket. The distance D is the maximum distance atwhich an arc will be struck between the pin and the socket under highvoltage alternating current conditions when the pin and socket areunused, i.e., are not contaminated with electrically conductivematerials from prior use. It has been found that by terminating thesleeve 48 at an end face 92 which is spaced longitudinally from thesocket 40 the resulting gap 90 apparently provides some volume which canbe occupied by the arc and which can immediately accommodate gasesgenerated at the surfaces of the arc-quenching material ofthe sleeve 48and the tip contacted by the arc. At the same time, the provision of agap 90, rather than arc-quenching material, in the vicinity of the arcreduces the amount of arc-quenching material upon which the arc can actto produce gas, thereby reducing somewhat the volume of gas generated.Additionally, the tubular member 52 which surrounds the gap 90 isexposed to the arc and since the tubular member 52 is electricallyconnected to the socket at portion 55, the tubular member can act as acontact to help carry current during arcing. Because the tubular member52 is fabricated of metal, the material of the tubular member will notevaporate as quickly as a plastic arc-quenching material under theinfluence of an arc. Furthermore, any metal vapor within the gap 99 willtend to condense upon the tubular member 52 since the tubular member isgenerally cooler than the pin 26, the socket 40, the tip 30 and thesleeve 48. Thus, the tubular member 52 itself, when exposed to the arcthrough the use of the gap 90, becomes an important component part inthe accommodation of the arc.

It has been determined that for optimum performance the longitudinalspacing between the end face 92 of the sleeve 48 and the confronting end94 of the socket 40 should be in the order of magnitude of at least onehalf the arc-strike distance D. Thus, the axial (longitudinal) length Lof the gap 90 should be no less than one-half the distance D. Since itis preferable that the arc be struck, at least initially, between thepin 26 and the socket 40, rather than between the pin and the exposedportion 96 of the wall of the tubular member 52, the inside diameter ofthe tubular member 52 at the exposed portion 96 of the wall thereof issuch that the exposed portion 96 of the wall of the tubular member isspaced radially from the path of travel of the pin 26, ie, the outsidediameter of the pin when the pin is engaged in the socket, a distancesufficient to provide the gap 90 with an annular configuration having aradial (lateral) width W no less than, and preferably slightly greaterthan, the axial length L of the gap '90. in any event, radial width Wshould be no less than the order of magnitude of onehalf the arc-strikedistance D.

As the connector element ages (that is, as the connector element is usedand gases are generated therein), electrically conductive material cancondense upon the end face 92 of the sleeve 48 and provide an electricalpath between the pin 26 and the wall of the tubular member 52 enablingan arc to be struck initially between the pin and the tubular memberrather than between the pin and the socket 40 as the pin is advancedtoward the socket. In order to aid in precluding such an occurrence, aportion 98 of the end face 92 adjacent the tubular member 52 is spacedlongitudinally further from the socket 40 than the portion 100 of theend face 92 which is contiguous with the path of travel of the pin 26 byreducing the outside diameter of the sleeve 48 at 102. Thus, any pathalong the end face 92 between the pin 26 and the tubular member 52 willhave a greater length than the lateral distance (equal to distance W)between the bore 50 and the tubular member 52. This reduction of theoutside diameter of the sleeve at 102 also serves to eliminate morearc-quenching material from the vicinity of the arc occupying the gapthereby further reducing the volume of gas generated by that arc.

Thus, by providing a gap 90 of prescribed length L and width W betweenthe sleeve 48 and the socket 40 and by surrounding the gap 90 with anelectrically conductive wall, preferably in the form of a metallictubular member 52, a means has been found by which gases generated by anare which must be struck as the pin 25 approaches the socket 40 can becontrolled and advantageously reduced in volume so as to render theconnector element in the form of bushing 34 more effective even underextreme conditions of high voltage short circuit or fault connection.Such a reduction in the volume of these gases thus improves theperformance and reliability of the connector element. In addition, theuse of a gap, as described above, within a connector element employed inlower voltage circuits where a fault, or short circuit, would notpresent conditions as severe as similar occurrences within high voltagecircuits, and the resulting reduction in the volume of gases generatedunder such conditions permits a concomitant reduction in the volume ofthe expansion chamber to a degree sufficient to eliminate the necessityfor two separate chambers connected by a valve means, a singlerelatively small chamber being sufficient to accommodate the gasesgenerated upon connection under fault and being limited enough in volumeto restrain gases generated upon disconnection under load. Furthermore,the utilization of a gap, as described above, in connection with anelectrical connector of the type which employs a vent will improve theperformance of such a connector in that the undesirable effects ofexpelling gas from the connector will be reduced by virtue of thereduction in the volume of expelled gases.

It is to be understood that the above detailed description of anembodiment of the invention is provided by way of example only. Variousdetails of design and construction may be modified without departingfrom the true spirit and scope of the invention as set forth in theappended claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

l. in an electrical device, such as an electrical connector element, inwhich electrical contact is to be made between at least a first contactand a complementary second contact under high voltage fault conditionsby movement of the first contact into engagement with the secondcontact:

means for guiding the first contact for movement along a path of travelleading to the second contact and providing a guide of arc-quenchingmaterial for receiving the first contact prior to engagement of thefirst contact with the second contact, said guide being spacedlongitudinally from the second contact in the direction of saidmovement; and

means for surrounding the space between the guide and the second contactand providing a wall of electrically conductive material juxtaposed withthe guide and the second contact and spaced laterally from said path oftravel, said wall being electrically connected to the second contact;

the longitudinal spacing between the guide and the second contact andthe lateral spacing between the wall and the path of travel providing agap having a longitudinal length no less than the order of magnitude ofone-half the distance between the first and second contacts at which anarc will be stmck between the contacts as the first contact approachesthe second contact under said high voltage fault conditions and alateral width no less than the order of magnitude of one-half saidarc-strike distance.

2. The invention of claim 1 wherein the lateral width of the gap is atleast as great as the longitudinal length thereof.

3. The invention of claim 1 wherein the first contact includes ametallic pin and the second contact includes a metal socket forreceiving the pin:

said guide includes a sleeve of arc-quenching material for receiving thepin, the sleeve being longitudinally spaced from the socket; and

said surrounding means includes a metallic tubular member overlappingthe sleeve and the socket and spaced laterally from the path of travelof the pin to surround the longitudinal spacing between the sleeve andthe socket with said wall;

the longitudinal spacing between the sleeve and the socket and thelateral spacing between the tubular member and the path of travelproviding said gap.

4. The invention of claim 3 wherein the guiding means include a tip ofarc-extinguishing material carried by the pin and receivable within thesleeve.

5. The invention of claim 3 wherein the lateral width of the gap is atleast as great as the longitudinal length thereof.

6. The invention of claim 3 wherein the sleeve includes an end faceconfronting the socket and spaced longitudinally from the socket, saidend face having at least a portion adjacent the tubular member spacedlongitudinally further from the socket than the portion of the end facewhich is contiguous with the path of travel of the pin such that a pathalong the end face between the pin and the tubular member will have agreater length than the lateral distance between the pin and the tubularmember.

7. The invention of claim 3 wherein the pin is cylindrical and has aprescribed diameter and the socket is cylindrical and has an internalbore of a diameter complementary to the diameter of the pin, and anoutside diameter;

the sleeve is cylindrical and has an inside diameter complementary tothe diameter of the pin and a prescribed outside diameter, said sleevebeing spaced axially from the socket; and

the tubular member is cylindrical and includes first portions having aninside diameter complementary to and overlapping with the outsidediameter of the sleeve and the outside diameter of the socket, and asecond portion surrounding the axial spacing between the sleeve and thesocket and having an inside diameter greater than the diameter of thepin such that the second portion is spaced radially from the outsidediameter of the pin when the pin is engaged in the socket;

said axial spacing and said radial spacing providing the gap with anannular configuration such that said longitudinal length is axial andsaid lateral width is radial.

8. The invention of claim 7 wherein the guiding means include a tip ofarc-quenching material carried by the pin and receivable within thesleeve 9. The invention of claim 7 wherein the radial width of the gapis at least as great as the axial length thereof.

10. The invention of claim 7 wherein the sleeve includes an end havingan end face confronting the socket and spaced axially from the socket,and the outside diameter of the sleeve is reduced adjacent said end suchthat a portion of the end face adjacent the tubular member is spacedaxially further from the socket than the portion of the end facecontiguous with the pin when the pin is engaged in the socket.

l 1. The invention of claim 3 wherein the longitudinal length of the gapand the lateral width thereof are each approximately one-half saidarc-strike distance.

12. The invention of claim 7 wherein the width of the gap isapproximately the same as the length thereof.

UNITED STATES PATENT oEETEE CETIFICATE 9F QOREC'HQN Pat nt N 3,654 ,590Dated April 4 1972 Inventor() Robert R. Brown It is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

In the name of the assignee, "Ameraca" should read Amerace Column 1,line 26, a comma should be inserted between "Additionally" and "there";Column 1, line 33, "ad" should read and Signed and sealed this 10th dayof October 1972.

(SML) Attest:

EDWARD M.FLETCHER,J'R. Attesting Officer ROBERT GO'ITSCHALK Commissionerof Patents USCOMM-DC 60376-P69 e u.S. GOVERNMENT PRINTING OFFICE: I9690-366-334 ORM PO-105O (10-69)

1. In an electrical device, such as an electrical connector element, inwhich electrical contact is to be made between at least a first contactand a complementary second contact under high voltage fault conditionsby movement of the first contact into engagement with the secondcontact: means for guiding the first contact for movement along a pathof travel leading to the second contact and providing a guide ofarc-quenching material for receiving the first contact prior toengagement of the first contact with the second contact, said guidebeing spaced longitudinally from the second contact in the direction ofsaid movement; and means for surrounding the space between the guide andthe second contact and providing a wall of electrically conductivematerial juxtaposed with the guide and the second contact and spacedlaterally from said path of travel, said wall being electricallyconnected to the second contact; the longitudinal spacing between theguide and the second contact and the lateral spacing between the walland the path of travel providing a gap having a longitudinal length noless than the order of magnitude of one-half the distance between thefirst and second contacts at which an arc will be struck between thecontacts as the first contact approaches the second contact under saidhigh voltage fault conditions and a lateral width no less than the orderof magnitude of one-half said arcstrike distance.
 2. The invention ofclaim 1 wherein the lateral width of the gap is at least as great as thelongitudinal length thereof.
 3. The invention of claim 1 wherein thefirst contact includes a metallic pin and the second contact includes ametal socket for receiving the pin: said guide includes a sleeve ofarc-quenching material for receiving the pin, the sleeve beinglongitudinally spaced from the socket; and said surrounding meansincludes a metallic tubular member overlapping the sleeve and the socketand spaced laterally from the path of travel of the pin to surround thelongitudinal spacing between the sleeve and the socket with said wall;the longitudinal spacing between the sleeve and the socket and thelateral spacing between the tubular member and the path of travelproviding said gap.
 4. The invention of claim 3 wherein the guidiNgmeans include a tip of arc-extinguishing material carried by the pin andreceivable within the sleeve.
 5. The invention of claim 3 wherein thelateral width of the gap is at least as great as the longitudinal lengththereof.
 6. The invention of claim 3 wherein the sleeve includes an endface confronting the socket and spaced longitudinally from the socket,said end face having at least a portion adjacent the tubular memberspaced longitudinally further from the socket than the portion of theend face which is contiguous with the path of travel of the pin suchthat a path along the end face between the pin and the tubular memberwill have a greater length than the lateral distance between the pin andthe tubular member.
 7. The invention of claim 3 wherein the pin iscylindrical and has a prescribed diameter and the socket is cylindricaland has an internal bore of a diameter complementary to the diameter ofthe pin, and an outside diameter; the sleeve is cylindrical and has aninside diameter complementary to the diameter of the pin and aprescribed outside diameter, said sleeve being spaced axially from thesocket; and the tubular member is cylindrical and includes firstportions having an inside diameter complementary to and overlapping withthe outside diameter of the sleeve and the outside diameter of thesocket, and a second portion surrounding the axial spacing between thesleeve and the socket and having an inside diameter greater than thediameter of the pin such that the second portion is spaced radially fromthe outside diameter of the pin when the pin is engaged in the socket;said axial spacing and said radial spacing providing the gap with anannular configuration such that said longitudinal length is axial andsaid lateral width is radial.
 8. The invention of claim 7 wherein theguiding means include a tip of arc-quenching material carried by the pinand receivable within the sleeve.
 9. The invention of claim 7 whereinthe radial width of the gap is at least as great as the axial lengththereof.
 10. The invention of claim 7 wherein the sleeve includes an endhaving an end face confronting the socket and spaced axially from thesocket, and the outside diameter of the sleeve is reduced adjacent saidend such that a portion of the end face adjacent the tubular member isspaced axially further from the socket than the portion of the end facecontiguous with the pin when the pin is engaged in the socket.
 11. Theinvention of claim 3 wherein the longitudinal length of the gap and thelateral width thereof are each approximately one-half said arc-strikedistance.
 12. The invention of claim 7 wherein the width of the gap isapproximately the same as the length thereof.